The buildings had no sprinklers, because each floor could be sealed off from the others in case of a fire. "There are shutters that would shut off the vertical openings [between floors] so that the fire couldn't travel from one floor to the other. That was the theory. When the danger had subsided they could evacuate."

After the planes crashed into the buildings, Swirsky said people in the floors above would have been trapped. They would have been unable to escape. The buildings were not designed to allow for a quick exit in case of emergency. Afterward, those trapped would have fallen with the buildings when they collapsed.